Triphenyl phosphate, isopropylated
MAK Value Documentation – Translation of the German version from 2016
Andrea Hartwig1 (Chair of the Permanent Senate Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area, Deutsche Forschungsgemeinschaft)MAK Commission2
1 Institute of Applied Biosciences, Department of Food Chemistry and Toxicology, Karlsruhe Institute of Technology (KIT), Adenauerring 20a, Building 50.41, 76131 Karlsruhe, Germany
2 Permanent Senate Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area, Deutsche Forschungsgemeinschaft, Kennedyallee 40, 53175 Bonn, Germany
Abstract
The German Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area has evaluated triphenyl phosphate, isopropylated [68937-41-7] to derive a maximum concentration at the workplace (MAK value), considering all toxicity end points. Available unpublished study reports and publications are described in detail. Isopropylated triphenyl phosphate has no irritant effects on the skin of rats and rabbits, and is not, or at most minimally, irritating to the eyes of rabbits. It belongs to the group of organophosphates and shows the typical delayed organophosphate neurotoxicity (axonal degeneration). The neurotoxicity decreases with increasing isopropylation. However, the most sensitive toxicological end points following repeated exposures are histopathological changes in the adrenal gland and ovary. The LOAEC in 90-day inhalation studies in rats and in hamsters was 10 mg/m3, the lowest tested concentration. Oral studies according to OECD TG 422 and TG 408 have revealed a LOAEL of 25 mg/kg body weight and day in rats. Neurotoxicity tests in hens have yielded a NOAEL of 20 mg/kg body weight and day. After scaling these NOAELs to a concentration at the workplace, a MAK value of 1 mg/m3 is derived. As the systemic effect is critical, isopropylated triphenyl phosphate is assigned to Peak Limitation Category II with the default excursion factor of 2, as no specific toxicokinetic data are available. No developmental toxicity was observed at 260 mg isopropylated triphenyl phosphate/kg body weight and day. Therefore, no damage to the embryo or foetus has to be expected and isopropylated triphenyl phosphate is classified in Pregnancy Risk Group C. Isopropylated triphenyl phosphate is not genotoxic in vitro or in vivo nor does it have cell-transforming activity. No data on carcinogenicity are available. Overall, the available data do not indicate that the substance should be classified as a carcinogen or a germ cell mutagen. Sensitizing potential was not investigated with isopropylated triphenyl phosphate, and similar compounds have led to inconclusive results. Absorption through the skin is low and does not relevantly contribute to systemic toxicity.
